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The 1960 Central Pacific Tropical Cyclone Season

NOTE:This excerpt was taken from A History of Tropical Cyclones in the Central North Pacific and the Hawaiian Islands 1832 - 1979, which was printed in 1981 by the US Department of Comerce, National Oceanic and Atmospheric Administration, in September of 1981. The author was Samuel L. Shaw of the Central Pacific Hurricane Center and the National Weather Service Forecast Office in Honolulu, HI.

The launching of the first meteorological satellite, TIROS I, in April 1960 announced a new era of tropical cyclone awareness and forecasting. Observations from meteorological satellites began to fill the data gap which had long existed in the tropical Central and Eastern North Pacific.

Early TIROS III data combined with indirect reasoning (Sadler, 1962) suggested a much greater frequency of tropical cyclones for this region than had been observed by conventional meteorological data. Rosendal (1962) presented an excellent summary of observed tropical cyclones over the Eastern North Pacific for the 15-year period 1947-1961 which were assumed to be of at least tropical storm intensity.

In this paper, in agreement with NWS areas of tropical cyclone forecast responsibility, those portions of the North Pacific east of longitude 140·W are designated as Eastern North Pacific. The area from 140·W to the International Date Line is designated the Central North Pacific (Figure 1). Rosendal's paper, concentrating on the Eastern North Pacific, listed an average of five tropical cyclones per year during 1947-1953. The average number doubled to 10 per year for the 1954-1961 period. He attributed that increase to improved aerial reconnaissance, increased shipping and better communications. Only four of the storms tracked by Rosendal, and later by De Angelis (1967), during the 1947-1953 period were observed to have crossed from the Eastern into the Central North Pacific. All of these storms were detected during 1954-1961.

The pre-satellite detection of tropical cyclones in the Central and Eastern North Pacific was dependent on ship reports. Therefore, the positions of first detection and the deduced storm tracks were mainly confined to areas along and between principal shipping routes.

Sadler (1963) examined TIROS V and VI data from nephanalyses published by the National Weather Satellite Center for the period August-October 1962 in order to detect cyclonic disturbances in the Central and Eastern North Pacific. He found 62 vortexes, 39 of which appeared to be of at least tropical storm strength. Those vortexes were determined to represent 22 different storms.

A comparison of these data and the conventional U.S. Weather Bureau (1962, 1963) monthly tropical storm summaries showed that only 5 of the 22 storms were detected by ships or other conventional means. One of the 5 was verified as an unnamed tropical storm by the ship GOLDEN STATE only in response to a TIROS alert message at the bottom of the last NWS advisory issued on another tropical storm (AVA) about 900 miles farther east.

Excerpts of the report received from Mr. G. J. Mueller, 3d Mate of the GOLDEN STATE, attest to the accuracy of Sadler's analysis:

"On the mid-watch 8/21/62 passed thru a very low pressure area. Barometer dropped from 29.82" (1009.8 mb) to 29.60" (968.5 mb) in a period of 1 hour. Winds encountered reach a maximum of force 8.

"This was predicted by satellite TIROS indicating a low pressure circulation in that area. Position of which was highly accurate. Force 8 winds lasted for a period of about 1 hour.

Nine storms were detected by TIROS south of the regular shipping lanes. Eight were detected within the shipping lanes but were not reported by shipping.

Using TIROS III pictures Sadler (1963) also found two storms of 1961 in the Central North Pacific which were not detected by conventional data. Six of the previously mentioned 22 storms found from TIROS V and VI imagery were located in the Central North Pacific.

Sadler's 1963 report was based on good photographic data over the tropical Eastern North Pacific from TIROS III during the latter 2 weeks of August 1961 and from TIROS V during late August and early September 1962. Occasional data were obtained during the remainder of September and October 1962 by TIROS V and VI. Consecutive days of possible photographic coverage over a specified tropical area were limited to about 20 out of a 65-day cycle, while occasional data could be obtained on about 30 additional days of the cycle from these low altitude polar orbiting satellites.